The present invention relates to a new and improved construction of an apparatus for picking or firing shuttles, especially projectile-like shuttles of a loom.
Generally speaking, the apparatus of the present development is of the type comprising at least one pair of driven rolls which can be brought into contact with opposite sides of the shuttles which are to be inserted into the weaving shed. The rolls of the pair of rolls each are rotatably mounted at a spring-loaded pivotal lever which can be pivoted about a stationary axis or shaft.
Equipment of this type has already been disclosed to the art in Swiss Pat. No. 536,889 and Swiss Pat. No. 558,437 of the same assignee as the instant application. There are provided a plurality of driven pairs of rolls arranged in succession in the shuttle picking or firing direction. At least part of the pairs of rolls simultaneously serve to brake the shuttles and they can be alternatively brought out of an ineffectual position into an effectual operative association or connection with the related shuttle.
This prior art equipment has not however been found to be suitable in practice since already after 200,000 to 400,000 load changes it becomes unusable. The reason for this is that there prevails an impermissibly high relative movement between the circumference of the rolls and the shuttles, so that owing to rapid wear at the projectile-like shuttles and the picking rolls the picking or the firing of the shuttles can no longer be controlled. A further notable disadvantage is that by virtue of the differential movements during shuttle firing or picking by a number of rolls, the wear becomes appreciably greater. This drawback is hardly enhanced by using a more improved construction wherein there is provided at the last pair of rolls a slipping clutch between the rolls and the drive.
It has also been contended in the publication "Melliand Textilberichte" 5/1968, page 535, that the technique of accelerating a thread-carrying projectile by means of rolls would never find significance in the loom or weaving technology.